1. FIELD OF THE INVENTION
The invention relates to a process for the preparation of m-bromo-benotrifluorides.
2. DISCUSSION OF THE PRIOR ART
It is known to prepare 3-bromo-4-chloro-benzotrifluoride by brominating 4-chloro-benzotrifluoride, using iron as a catalyst (J. Am. Chem. Soc. 71, 2659 (1949)). The yield of the process is about 55%. A large proportion of the 4-chlorobenzotrifluoride employed is saponified to the corresponding carboxylic acid during the process. The 4-chlorobenzotrifluoride must in turn be prepared by fluorinating 4-chlorobenzotrichloride.
It is also known to carry out the bromination of trifluoromethylbenzenes in the presence of antimony pentachloride as a catalyst (J. Am. Chem. Soc. 72, 1651 (1950)). In this reaction, the yield is only about 30 to 35%.